Nature Materials

Granular scaffolds have emerged as promising platforms for tissue regeneration, offering injectability and cell-scale porosity that support robust cell infiltration and tissue formation. However, the isotropic pore structure of spherical building blocks does not provide the directional cues needed to guide organized tissue formation. Addressing this requires asking not just whether granular scaffolds can be made anisotropic, but whether directional cues persist across the pore network at scales relevant to cell behavior. Using high aspect ratio GelMA hydrogel fibers as building blocks, we demonstrate that spherical granular materials lose orientational coherence at the cellular scale, confirming that isotropic building blocks are fundamentally incapable of providing structural guidance beyond individual pore neighborhoods. In contrast, fibrous building blocks extend persistence into the multicellular range, occupying an intermediate architectural regime exhibiting locally coherent but globally variable organization, rather than simple isotropic or uniaxial alignment, that has previously been inaccessible to granular scaffold design. We show this regime is functionally meaningful: myotubes undergo contact guidance through locally persistent but globally variable pore structure, and greater persistence is associated with increased myotube elongation and multinucleation in primary human muscle progenitor cells. Together these results expand the design space for granular scaffolds beyond pore size and porosity, and establish persistence as a variable linking granular scaffold architecture to organized tissue formation.

Directed cell migration underlies many biological phenomena, from embryonic development to tumor metastasis and organ fibrosis. Most cells typically migrate toward stiffer regions of their extracellular matrix -a behavior known as positive durotaxis. Here we show that culture on rigid plastic reinforces this response, whereas preconditioning in soft 3D physiomimetic environments reprograms migration towards softer environments, a phenomenon known as negative durotaxis. Fetal rat lung fibroblasts preconditioned in 3D physiomimetic hydrogels exhibited negative durotaxis and accumulated near [~]5 kPa, corresponding to the physiological stiffness of the lung. In contrast, genetically identical cells maintained on conventional 2D plastic substrates migrated up stiffness gradients, toward stiffer regions. Although both populations displayed a biphasic force-stiffness relationship, they differed in force magnitude and cytoskeletal organization. Molecular-clutch modeling revealed that durotaxis reversal emerges from two distinct mechanical regimes: a mechanosensitive, high-motor-clutch state that stabilizes adhesions on stiff substrates and drives positive durotaxis, and a low-motor, weak-adhesion state in which clutch slippage on the stiff side causes negative durotaxis. Our results show that durotaxis direction is not an intrinsic cellular property. Rather, it emerges from the interplay between motor activity and adhesion dynamics and can be tuned by culture conditions.

Engineered living materials (ELMs) promise genetically programmable functions by coupling biological regulation to synthetic material responses. Here, we introduce genetically encoded, reversible shape-morphing in a peptide-crosslinked polyethylene glycol (PEG) hydrogel whose network density is modulated by opposing enzymatic pairs that induce crosslinking or hydrolysis. This molecular programmability alternates the hydrogel between deswelling and swelling/disintegration and produces 2 - 5-fold changes in mechanical properties. By fabricating a bilayer hydrogel with an inert layer, these molecular modulations are translated into a reversible and directional motion with angular bending motions exceeding 80{degrees}. Further, by embedding genetically engineered bacteria or interfacing mammalian cells, producing the relevant enzymatic cues, the reversible shape-morphing of these ELMs is programmed at the genetic level. We further demonstrate genetically programmed, autonomous reversible bending in a bilayer hydrogel controlled by out-of-equilibrium counteracting biochemical reactions with dynamically changing respective reaction rates. This work establishes a concept where coordinated polymer/peptide material engineering and synthetic biology yield autonomous shape-morphing ELMs, opening avenues toward biohybrid soft robotics, adaptive microfluidic systems, and dynamic biomedical interfaces.

Collective cell migration drives tissue morphogenesis, repair and remodeling, and is often accompanied by transitions from solid-like to fluid-like states. While such tissue fluidization has been linked to physical parameters such as cell density, shape and activity, how it is actively regulated by mechano-chemical interplay remains unclear. Previous research has shown that transient attenuation of actomyosin contractility induces a transition from pulsatile, spatially confined motion to coherent, persistent long-range collective flow; however, the underlying cellular and signaling mechanisms remain unclear. Here we uncover the mechanistic basis by which transient perturbation of cell contractility reprograms the migration mode of confluent epithelial cells into a leader-like, fluidizing state, by combining kinase-reporter live imaging, force measurements and mathematical modeling. This transition arises from coordinated changes in cell morphology, mechanics, and signaling, including reduced cortical tension, enhanced cell-substrate adhesion and traction forces, and increased tissue deformability. At the signaling level, this process is accompanied by a rewiring of extracellular signal-regulated kinase (ERK)-mediated mechanotransduction toward a protrusion-coupled mode that sustains migration even under fully confluent conditions. Consistently, a multicellular computational model further demonstrates that protrusion-driven migration is sufficient to promote shape-velocity alignment and drive a transition from caged to flocking-like collective states. Together, our results identify transient mechanical relaxation as a trigger for an intrinsic leader-like state that fluidizes epithelial confluent tissues through coordinated remodeling of cytoskeletal, adhesive, and signaling systems.

The mechanical toughness of bone and teeth relies on residual stresses generated during mineralisation, where the dehydration of collagen fibrils leads to contraction, putting the mineral phase under compression. While macroscopic stiffening of collagen upon drying is well-documented, the atomic-level structural rearrangements driving this phenomenon have remained elusive. By performing molecular dynamics simulations, we demonstrate that collagen contraction is not homogeneous but is driven by specific charged motifs. We identify a critical sequence-dependent rule for contraction: oppositely charged side chains must be separated by at least four residues to drive backbone contraction. While salt bridges can form between side chains at a distance less than four residues without perturbing the helix, those at greater distances cannot form without rupturing backbone hydrogen bonds. Consequently, dehydration forces these distant charges together, breaking local backbone structure and driving collagen contraction. These findings imply that collagen sequences are evolutionarily tuned to actively control tissue mechanics and redefines collagen as an active mechanical element rather than a passive scaffold. Furthermore, this framework provides a molecular basis for understanding mechanical failure associated with pathologies and ageing, while simultaneously opening avenues for designing bio-inspired materials with tunable pre-stress and fracture resistance.

The spatial arrangement of cells is fundamental to the mechanical and functional integrity of three-dimensional (3D) tissues, yet engineering spatially well-controlled tissue architectures remains challenging. Here, we computationally investigated how layered tissue architectures can be designed by modulating cell-cell interfacial tension. We performed simulations using a 3D vertex model and systematically varied interfacial tension magnitudes. The simulations generated a range of layered tissue architectures, including planar monolayers, bilayers, and structurally stratified states. In homogeneous cell populations, increasing interfacial tension drove transitions from monolayer to structurally stratified configurations. In heterogeneous populations, differential interfacial tensions induced out-of-plane cell sorting and the formation of compositionally sorted multilayers. Moreover, a recursive tension design strategy enabled hierarchical organization of multiple cell types into separate layers. Notably, this recursive scheme uses only two tension levels (high vs. low) assigned across interfaces and can, in principle, be extended to specify layered architectures with an arbitrary number of layers. Together, these results identify cell-cell interfacial tension as a tunable mechanical parameter for regulating layered tissue architecture and provide design principles for layered tissue engineering and regenerative medicine.

The basement membrane (BM) is a specialised extracellular matrix tightly tethered to epithelial tissues. While the viscoelastic response of epithelial cells to external deformation has been widely studied, the dynamic mechanical role of its underlying BM remains poorly understood. This is mainly due to its thin, dense, non-fibrillar structure and limited number of model systems that allow live fluorescent imaging of the BM components. Using the Drosophila wing disc, we investigate the BMs response to sustained deformation and find that the tissue retains memory of its shape for up to four hours, enabled by the BMs initial elasticity. However, prolonged deformation leads to BM network rearrangement and loss of mechanical memory, resulting in permanent shape change. Our findings reveal that the BM sets the long-term viscoelastic timescale of epithelial tissues which plays a critical role in maintaining tissue architecture under mechanical stress.

Neuroelectronic interfaces hold great promise to restore functions in neurological disorders or motor dysfunctions, but current devices struggle to integrate seamlessly within living tissues. Here we report a transformative approach to create bionic neurons that autonomously build integrated fluorescent fibrils and demonstrate their role as neuromodulators. Using a combination of cell biology, ultrastructural, imaging and nanospectroscopical approaches, we deciphered the unique biosynthetic pathway employed by the cells to self-fabricate these nanoelectronics and uncover their hybrid structure. Importantly, patch clamp recordings revealed their neuromodulatory potential, through the perturbation of membrane electrical properties and the early rising phase of the action potential. Deciphering how basic molecular elements self-organize into complex architectures within biological environments could unlock the ability to engineer natural electroactive systems directly inside living organisms. This capability could be used to create conductive pathways between arbitrarily defined neurons, microcircuits, or nervous system regions, effectively writing connections into living brains.

Compartmentalization is a defining feature of cellular systems, yet how early compartments could undergo repeated cycles of growth, division, and content organization without complex chemistry remains unresolved. Here we study a minimal membrane-based system subjected to periodic hydration- dehydration cycles, mimicking fluctuating physical environments on the early Earth. We show that cyclic environmental conditions alone drive a sequence of reproducible compartment dynamics, including macromolecule encapsulation, membrane growth, division, and the generation of a highly crowded interior. These processes emerge from biophysical transformations of a single-component membrane and do not require any chemical reactions or metabolic activity. Importantly, compartments retain their structural integrity across multiple cycles, enabling repeated encapsulation without loss of individuality. Our results demonstrate that fluctuating physical conditions can be transduced by membrane biophysics into sustained, cell-like cycles, challenging the view that primordial cellular dynamics necessarily required chemically driven growth and division.

Gene order is a powerful design principle for protein nanomachines. In nature, gene organisation ensures the precise assembly of functional protein nanostructures. We demonstrate how genetic repositioning of the key structural gene pduN, within the operon encoding a self-assembling protein nanocompartment, sculpts the morphology and function of bacterial microcompartments (BMCs). Relocating pduN to new operonic positions dramatically altered the size, shape, and catalytic output of BMCs, despite identical protein sequences. These shifts reveal how gene order may control nanoscale assembly and compartmentalised function. Our findings establish operon architecture as a programmable genetic framework for nanostructure morphogenesis and provide a synthetic biology strategy to engineer self-assembling nanodevices with customised geometries and activities.

Adoptive T cell therapy for solid tumors is limited by poor persistence of CD8+ T cells, a dysfunction that is often programmed during ex vivo expansion. Here, we show that, when biochemical inputs are held constant,substrate mechanics alone can direct durable anti-tumor function in primary human CD8+ T cells. Using polyacrylamide (PA) hydrogels of defined stiffness (soft [~]1 kPa; stiff [~]55 kPa) in both flat and bead formats, we first establish that contact geometry dominates early activation, whereas substrate stiffness governs the 14-day expansion trajectory. Across the rapid expansion protocol, flat PA substrates sustain proliferation, limit PD-1/LAG-3 acquisition, and preserve a balanced effector-regulatory cytokine profile. In contrast, Dynabeads-expanded cells exhibit net cell loss and a more pronounced decline in cytokine output over time. To define the underlying programs, RNA-seq identifies a 125-gene biomimetic core shared by both PA conditions but absent from Dynabeads, encompassing proliferation, OXPHOS, mechanobiology, and a stem-like precursor (Tpex) signature. Consistent with these transcriptional differences, metabolic profiling shows that flat soft PA best preserves dual glycolytic and mitochondrial capacity at day 14, indicating enhanced bioenergetic flexibility. Functionally, PA-primed CD8+ T cells display superior cytotoxicity against MDA-MB-231 and MCF-7 breast cancer cells in both 2D and collagen-based 3D co-cultures, with this advantage maintained under matrix constraints that mimic solid tumor microenvironments. Together, these findings establish substrate mechanics as a tunable and functionally decisive design parameter for engineering durable, solid-tumor-effective CD8+ T cell products in preclinical in vitro models of solid tumors.

Fibrotic responses at biomaterial-tissue interfaces limit implant integration and regenerative healing, yet how the interaction between biomaterials and the extracellular matrix (ECM) regulates fibroblast activation remains poorly understood. Granular hydrogels including microporous annealed particle scaffolds (MAP) reduce fibrosis, while chemically and mechanically matched hydrogels do not, suggesting a dominant role for scaffold architecture. In this model, MAP scaffolds allow collagen infiltration and form physically continuous composites, whereas hydrogels exclude collagen and generate interfacial slip planes. To isolate how biomaterial architecture influences extracellular matrix (ECM) integration and fibroblast activation, we developed a reductionist in vitro model that integrates collagen type I with either microporous annealed particle (MAP) scaffolds or chemically and mechanically matched bulk hydrogels. This physical integration stabilizes collagen architecture, limits fibroblast-mediated matrix compaction, suppresses contractility, and attenuates myofibroblast transition. Fibroblasts in mechanically integrated environments exhibit reduced expression and nuclear localization of NF-{kappa}B and are enriched for quiescent phenotypes. Together, these findings identify biomaterial-ECM physical continuity as a design principle for limiting fibrotic signaling.

Synthetic living constructs, which lack the long histories of selection in ecological contexts that shape behaviors of conventional organisms, offer an important complement to traditional studies of learning. Could novel biobots exhibit sensing and memory of experiences? Here, we investigated the effects of chemical stimuli on basal Xenobots - autonomously motile entities derived from Xenopus embryonic ectodermal explants (with no additional sculpting or bioengineering). We quantified and characterized the coordinated ciliary activity that generates fluid flow fields guiding the trajectory of Xenobot motion. We also show distinct and specific changes in Xenobot behavior after brief exposure to Xenopus embryonic cell extract and to ATP. These two experiences produced distinct, long-term, stimulus-specific memories, detectable through both transcriptional and physiological signatures. Exposure to specific environmental stimuli induced alterations in the spatiotemporal patterns of calcium signaling across Xenobots. Together, these data lay a foundation for characterizing the capabilities of synthetic cellular collectives to sense and discriminate among stimuli, as well as store functional information in a non-neural context. Understanding behavioral competencies in novel, non-neural systems have broad implications across evolutionary biology, behavioral science, bioengineering, and bio/hybrid robotics.

Cells use post-translational modifications (PTMs) to reconfigure biomolecular condensates across length scales, space, and time.1,2 While charged PTMs are well-known electrostatic switches,3,4 how ubiquitous neutral PTMs shape condensate plasticity and hierarchy remains unclear. Here, we establish a set of design principles for using site-specific lipidation, a class of neutral hydrophobic PTMs, to rationally control properties and interactions of engineered biomolecular condensates. Through systematic analysis of over 80 lipidated synthetic intrinsically disordered proteins (IDPs), we uncovered two distinct axes of control. First, the interplay between the lipid and the local three-residue sequence of its attachment site acts as a programmable switch for cohesion--the homotypic interactions that define the material state of the condensed phase-- directing assemblies toward dynamic liquids, arrested gels, or ordered fibrillar solids. Second, the lipid, together with the global properties of the IDP scaffold, tunes adhesion--the heterotypic interactions that govern condensate miscibility and hierarchical organization. We harnessed these principles to rationally engineer complex, multi-phase architectures and create hybrid hydrogels with programmed microstructure and material properties that guide the morphogenesis of functional intestinal organoids. These findings establish a new framework for lipoengineering advanced biomaterials and provide a blueprint for dissecting structure-property relationships across diverse classes of PTMs.

Understanding protein phase separation in cellular environments remains a major challenge, as ex vivo assays often fail to capture the influence of environmental context - such as crowding, multimodal interactions, and the dynamic properties of the cytosol or nucleus. Here, we introduce programmable DNA-based protonuclei (PN) as nucleus-inspired compartments to probe phase separation of the neurodegeneration-linked protein FUS. We show that FUS partitioning and condensate formation are highly sensitive to nucleic acid sequence, spatial confinement, and viscoelastic properties of the PN core. Notably, classical test-tube affinity assays fail to predict protein behavior within the crowded and multivalent PN environment. By tuning DNA crosslinking, we modulate condensate dynamics and suppress liquid-to-solid transitions of FUS - a hallmark of disease. These findings demonstrate that multivalent, confined environments fundamentally reshape protein-nucleic acid interactions and phase behavior. The PN platform complements test-tube assays and complex cellular settings and enables to dissect nuclear condensates under controllable conditions.

Protein immunotherapies can elicit potent tumor rejection, but reversible target engagement, incomplete tumor retention, and systemic leakage often erode spatial control. Here, we develop covalently anchored tumor immunotherapeutic proteins (CATIPs), a modular platform that uses proximity-enabled covalent chemistry to immobilize immune cues on tumor-cell surfaces after intratumoral administration. CATIPs combine tumor-targeting nanobodies with payloads for T cell engagement, co-stimulation, and cytokine support. In human PBMC-reconstituted NSG mice, CATIPs completely eradicated treated EGFR-positive tumors, outperforming matched non-covalent proteins while limiting redistribution, systemic T cell activation, cytokine release, xGVHD-associated morbidity, and on-target, off tumor toxicity. In immunocompetent melanoma models, CATIPs remodeled the tumor microenvironment, expanded antigen-specific CD8+ T cells, induced antigen-restricted abscopal control, and generated durable protection against local and metastatic rechallenge. CATIP-engineered tumor cells further functioned as whole-cell vaccines. Thus, covalent tumor anchoring converts local protein delivery into tumor-surface immune programming, enabling systemic, tumor-specific, durable antitumor immunity while limiting systemic immunopathology.

The ability to induce tissue regeneration on demand using biomaterials remains a major goal in biomedical research, yet significant challenges persist. Among the most advanced biomaterial models, the nanofiber-hydrogel composite has demonstrated a striking ability to induce soft adipose tissue remodeling at the injection site without incorporating exogenous biological cues.1,2 However, the underlying mechanisms that drive such a tissue response remain unclear. Here, we show that biomaterial-induced tissue remodeling is driven by sustained and controlled inflammation mediated by macrophages in strong communication with fibroblasts. Notably, both pro-inflammatory and anti-inflammatory signals remained elevated during this process in the long-term, challenging the prevailing notion that inflammation opposes remodeling. Using macrophage depletion in mice, we demonstrate that macrophages are essential for this process. Single-cell RNA sequencing further revealed robust fibroblast-to-macrophage signaling, contrasting with the conventional macrophage-to-fibroblast paradigm, and identified unique Spp1 macrophages and Ctla2a fibroblasts within the remodeling niche. These findings provide a comprehensive view of the immune landscape in biomaterial-induced tissue remodeling, highlighting key cellular interactions, prolonged kinetics, and unexpected signaling pathways. By defining key targets and fundamental principles, this work has broad implications for advancing biomaterial-induced tissue regeneration.

Cells can experience time-varying mechanical cues, particularly when navigating through changing and complex microenvironments. Yet whether and how cells retain and use a short-term mechanical memory of recent deformations remains unclear. Here we show that, in glioblastoma cells, this memory is encoded by transient cytoskeletal anisotropy. Using uniaxial magneto-mechanical actuation aligned or perpendicular to the cell long axis, nanoindentation, and selective cytoskeletal perturbations, we find that distinct architectures of the actin cytoskeleton drive opposite mechanical responses: actin stress fibers mediate stiffening under stretch, whereas the actin cortex underlies softening under perpendicular loading. Vimentin intermediate filaments are essential to stabilize actin organization under load, preserving deformation-specific mechanics. Quantitative imaging reveals that mechanical actuation induces network-specific alignment and anisotropy, stronger for actin than vimentin, that persists transiently after unloading and bias subsequent responses, revealing a short-lived, deformation-dependent mechanical memory. To integrate these observations, we develop a multi-network constitutive model that links cytoskeletal architecture and loading history to cell-scale mechanics, reproducing both the asymmetric mechanical responses and the measured reorganization dynamics. These findings provide a structural basis for short-term mechanical memory and suggest how cancer cells could exploit residual anisotropy to adapt to fluctuating solid stresses and confinement, transiently biasing polarization, force transmission, and directional persistence during invasion. They also identify vimentin-actin coupling and the kinetics of cytoskeletal remodeling as potential levers to limit the mechanical adaptability of invasive cancer cells.

A central problem in soft and biological physics is how molecular-scale activity and remodelling coarse-grain into emergent mechanical laws at larger scales. In growing cell walls (polymeric composite materials that surround 90% of living organisms cells) irreversible deformation is not controlled by elastic stress alone. Instead, growth depends on the interplay between energy storage, dissipation, and the local timing of viscoelastic relaxation. Although dynamic atomic force microscopy (AFM) resolves storage and loss moduli (E', E'') of living walls at nanometre resolution, these observables have remained phenomenological and disconnected from constitutive field variables. Here we introduce a physics-based inversion framework that converts AFM measurements of epidermal cells of living Arabidopsis plants into spatially resolved fields of stiffness k, viscosity , and relaxation time{tau} . By analysing the spatial gradients of E' and E'', we uncover organized mechanical heterogeneities governed by cellular confinement and stress focusing. We demonstrate that the local relaxation time is encoded directly in the coupling between storage and dissipation, yielding the pointwise relation{tau} = (1/{omega}) {partial}E/{partial}E, where{omega} is the indentation frequency. This relation enables model-independent extraction of mechanical timescales and establishes a general route from nanoscale non-equilibrium rheology to continuum descriptions of growth in living and active soft materials. SignificanceHow molecular-scale activity gives rise to tissue-scale form is a central challenge in biological physics. Although growth is fundamentally a non-equilibrium mechanical process, experimental measurements at the nanoscale have not been directly connected to the constitutive parameters that govern morphogenesis. We introduce a framework that converts dynamic atomic force microscopy maps of storage and loss moduli into spatially resolved fields of stiffness, viscosity, and relaxation time in living cell walls. By revealing that mechanical relaxation is encoded in the local coupling between elastic storage and viscous dissipation, our work provides a route from nanoscale rheology to growth-relevant mechanical timing. This establishes a quantitative bridge between molecular remodeling and continuum mechanics, enabling direct experimental constraints on multiscale theories of morphogenesis.

Curli fibers produced by Escherichia coli are functional amyloids that activate Toll-like receptor 2 (TLR2), initiating innate immune responses at mucosal surfaces. While microbiome-derived curli contribute to host-microbe interactions, their intrinsic immunostimulatory activity limits their utility as programmable scaffolds for engineered probiotic systems, and dysregulated TLR2 activation has been linked to inflammatory bowel disease, systemic lupus erythematosus, neurodegeneration, and sepsis. Here, we engineered E. coli Nissle 1917 to produce modified curli fibers designed to inhibit TLR2 through two mechanistically distinct strategies: steric shielding via silk-elastin-like protein sequences, and direct receptor antagonism via a known TLR2 antagonist, staphylococcal superantigen-like protein 3 (SSL3). Both engineered variants assembled into structurally intact amyloid fibers and exhibited significantly reduced intrinsic TLR2-dependent NF-{kappa}B activation in reporter cells. In competitive inhibition assays against structurally diverse TLR2 agonists, the SSL3 fusion achieved near-complete inhibition maintained under rising agonist load, while steric shielding provided moderate, agonist-class-dependent inhibition. In primary human monocyte-derived dendritic cells, the SSL3 fusion robustly attenuated IL-8 secretion and transcriptional induction of IL-8, IL-6, and IL-1{beta}, whereas steric shielding produced only partial attenuation that did not translate to broad inflammatory suppression. These results establish engineered curli as a tunable platform for receptor-specific modulation of innate immune signaling and highlight the broader potential of modular microbial amyloids as programmable interfaces for engineering host-microbe interactions at mucosal surfaces. IMPORTANCEBacteria residing in the gut produce protein fibers called curli that potently activate the immune system through a receptor called Toll-like receptor 2 (TLR2). While TLR2 plays a beneficial role in maintaining gut health, its overactivation drives chronic inflammation in conditions including inflammatory bowel disease, autoimmune diseases, neurodegenerative diseases, and sepsis, and curli fibers have been directly implicated in several of these conditions. Here, we engineered curli fibers produced by the probiotic E. coli Nissle 1917 to inhibit TLR2 activation, transforming a naturally inflammatory bacterial fiber into a programmable immune modulator. We demonstrated that direct receptor antagonism, rather than steric shielding, is required for effective immune modulation in primary human immune cells, establishing a design principle for engineering bacteria-derived fibers as programmable interfaces with host immunity. The modularity of the curli scaffold positions this platform as a broader tool for programming interactions between probiotic bacteria and the mucosal immune system.